Open GL Render. Anti-aliasing differences
OpenGL rendering in the VSE ignores the AA settings because it just pipes the viewport output through while


  Render -> OpenGL Render Animation


is more like an own render engine utilizing OpenGL. The OpenGL AA setting is only used by that "engine".

You can still get AA by setting the resolution of your original scene way bigger (like 400%) than the VSE scene. Blender will first render the scene really big in OpenGL and then scale it down in the VSE, wich essentially results in antialiasing.